Classification of mental disorder involves the identification of a group or pattern of mental symptoms that reliably occur together to form a type of disorder. This allows psychiatrists, doctors and psychologists to easily identify groups of similar patients. A diagnosis can be made, and a suitable treatment can be developed and administered to all those showing similar symptoms.
The DSM (Diagnostic and Statistical Manual of Mental Disorders) defines abnormality as a clinically significant syndrome associated with distress, loss of functioning, and an increase in the risk of pain or death. The DSM is a manual with over 200 specific diagnostic categories for mental disorder and lists the specific diagnostic criteria that have to be met for a diagnosis to be given.
However, one of the largest problems of diagnosing patients is whether or not the diagnosis is valid or reliable. Reliability is whether the same consistent diagnosis would be made for the same group of symptoms, and validity is whether a correct diagnosis is made.
There are two types of reliability. Inter-rater reliability is assessed by asking more than one practitioner to make a diagnosis for the same person and to see whether this diagnosis is consistent. Beck et al found that assessment on diagnosis for 153 patients, where each patient was assessed by more than 2 psychiatrists, was only 54%. This shows the unreliability of diagnosis. Similarly, Cooper et al found that New York psychiatrists were twice as likely to diagnose schizophrenia than London psychiatrists, who were twice as likely to diagnose mania or depression, when shown the same video-taped clinical interviews. This suggests that psychiatrists may be influenced by their culture beliefs when making a diagnosis. Lipton and Simon randomly selected 131 patients from a psychiatric hospital and attempted to re-diagnose them. This diagnosis was compared with the original diagnosis and found that of the original 89 patients who were diagnosed with schizophrenia, only 16 received this on re-evaluation. This clearly shows the unreliability of diagnosing patients, and how different psychiatrists will come up with different diagnosis.
Test-retest reliability is concerned with whether the same patient will receive the same diagnosis if assessed more than once by the same psychiatrist. Mary Seeman completed a literature review examining evidence relating to the reliability of diagnosis over time. She found that initial diagnosis of schizophrenia, especially in women, are more susceptible to change as clinicians found out more and more about their patients.
This clearly shows the unreliability of diagnosing patients. Although the DSM is constantly improving to better improve reliability, psychiatrists are still human and they are bound to make mistakes when diagnosing patients. Many factors need to be considered when making a diagnosis, such as their own researcher bias (reflexivity) and cultural bias.
Validity can also be a problem in diagnosis. Rosenhan (1973) conducted a study where 8 normal patients would try to gain admittance to psychiatric hospitals. These patients claimed to be hearing unfamiliar voices in their heads. All but one were admitted with schizophrenia. The patients were told to stop displaying the symptoms, and they were all discharged after 19 days. However, they were stigmatized with the label "schizophrenia in remission". Rosenhan was not satisfied with the results that normal patients could be classified as abnormal. He told psychiatrists that pseudo-patients would try to gain admittance to the hospital. In fact, there were no pseudo-patients, but 41 real patients were judged with great confidence to be a pseudo-patient by at least one member of staff. Rosenhan concluded that it was not possible to distinguish between sane and insane in psychiatric hospitals. This study shows good reliability, but poor validity in that normal patients could be given a diagnosis. However, there are criticisms of this study. Firstly, the staff at the hospital are not entirely to blame as the participants admitted themselves and told the staff about their symptoms. The staff was simply just doing their job at identifying the symptoms and making a diagnosis. In real life, doctors are not normally confronted with people wishing to be admitted to psychiatric hospitals. The sample was too small, so there is a problem of whether it can be generalized.
In conclusion, there will always be issues of validity and reliability in diagnosis. Certain groups of people will be more likely to receive a diagnosis to a disorder compared to others, and it is very difficult to remove the subjectivity and bias of practitioners from the diagnostic process. Psychiatrists will need to be careful when diagnosing patients, as once diagnosed the life of the individual will be changed forever.
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